Build your own Apollo Guidance Computer

Brent Hilpert hilpert at
Wed Dec 20 15:49:30 CST 2006

"William Donzelli"  writes:
> I think it was the early Cray-1 line. Four chip types - 2 gates, a
> flip flop, and a memory chip.
> To me, it seems like a really dumb idea. [...]

Richard wrote:
> To me it seems like a smart idea.  Concentrate on a few chips so that
> you can get the manufacturing yields up, the cost per component down,

While you two duke it out over the manufacturing practicalities :), I just have
to add that my interest in a processor made from a single gate type was just
for the esthetics of a 'universal machine made from a universal gate', or (to
be high-falutin' about it) a physical embodiment of a fundamental principle.

While the Cray-1 may have been a little late for such a design philosophy,
apparently there was a period in IC development where it made practical sense.
Aside from the AGC, I have an application note from RCA from 1967 for a small logic
family (ECCSL Emitter-Coupled Current Steered Logic) composed of just 3 IC types:
  CD2150 dual 4-in gate
  CD2151 dual 4-in gate (different output drive specs from 2150)
  CD2152 8-in gate
The app note includes diagrams for building standard functions (flip-flops, shift
register, counters, adders, etc.) from only those ICs.
No idea what equipment/machines they may have been used in.

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